BIOL 200 Lecture Notes - Lecture 29: Rna Polymerase Iii, Mating Type, Telomere
Document Summary
The power of yeast genetics and biochemistry: three genetic loci on chromosome iii genetically control the mating type of. Saccharomyces cerevisiae: the hmlalpha (for alpha mating type) and hmra (for a mating type) loci must be silenced otherwise the cells will be diploid a/alpha and cannot mate. A yeast can only mate with a haploid that is different from itself. When mother cell buds, she changes mating types (so that she can mate with daughter if need be) Genetic screen identi ed factors required for repression of the silent mating type loci: rap 1: Binds to dna in the region of the silencer. Also binds to repetitive sequence in telomeres: sir 1: (silent information regulator) Cooperates with rap 1 and is important for binding the silencer region in the silent mating type loci: sir 2, 3, 4: Bind to hypoacetylated histone tails (h3, h4) and recruits sir 2.
